In a by-wire brake system at least some of the traditional components such as the pumps, hoses, fluids, belts and brake boosters and master cylinders are replaced with electronic sensors and actuators.
There is a need for redundant electro-hydraulic and electro-pneumatic control circuits for trailer brakes in a by-wire brake system. The circuits must be capable of functioning even if one of the internal components fail, while at the same time, still achieving all of the requirements for a hydraulic or pneumatic trailer brake system.